Charles Darwin once remarked, “It is hardly an exaggeration to say that Nature tells us, in the most emphatic manner, that she abhors perpetual self-fertilization.” And yet, Kobe University botanist SUETSUGU Kenji knows of a few islands in Japan where orchids reproduce without ever opening their flowers. He says: “I’ve long been captivated by Darwin’s skepticism about plants that rely entirely on self-pollination. When I found those non-blooming orchids, I felt this was a perfect chance to directly revisit this issue. The apparent defiance of evolutionary common sense made me wonder what precise conditions — both environmental and genetic — would allow a purely self-pollinating lifestyle to emerge, let alone persist.”

On the Northern Ryukyu Islands of Kuroshima, Takeshima and Yakushima exist the only wild populations of plants known to reproduce solely by self-pollination. “Our group spent over ten years working with local plant enthusiasts, monitoring more than a hundred individual plants across several islands, so we can say with certainty that these orchids never open their flowers in their natural habitats,” explains Suetsugu. He and his team decided to subject these populations to genetic analysis that can detect minute differences even between closely related individuals, which allowed them to track gene flow and relatedness.

In the journal Proceedings of the Royal Society B, the Kobe University-led team now reports that the extreme genetic uniformity between the plants in each species proves that they are truly purely self-pollinating. In addition, they also found that the two species each arose from insect-pollinated species that already have a very low degree of genetic variation in this geographic region. The variation is so low, in fact, that even though pollen might get transported from one plant to the next, it’s nearly identical to self-pollination.

This is only made worse by another observation Suetsugu made: The cross-pollinating relatives on these islands rely on fruit flies with limited flight ability. The animals thus only pollinate, if they pollinate the plants at all, flowers of the same plant or of those that live very close by, even further reducing the benefit of insect pollination. Suetsugu explains: “Darwin’s statement was motivated by the idea that a purely self-pollinating lineage would accumulate harmful mutations and eventually face an evolutionary dead end. Yet our findings show that for the relative species with open flowers, the real genetic payoff for outcrossing might be marginal, giving the self-pollinating orchids, which are more successful at producing fruit, an evolutionary edge.”

As it turns out, Darwin’s skepticism might not have been unfounded. Another result of the Kobe University study is that even with conservative estimates, these self-pollinating species are at most 2,000 years old. Given that there are no other known examples of purely self-pollinating plants in the wild, such species might be ephemeral. “The fact that these orchids truly never outcross raises intriguing questions about their long-term viability, especially under pressures like habitat fragmentation and climate change,” says Suetsugu. He nevertheless is proud of his team’s findings, saying, “Each new data point, each newly described species, brings me closer to grasping the full spectrum of evolutionary possibilities.”

This research was funded by the Japan Society for the Promotion of Science (grants JP15K18470, JP17H05016 and JP18K06408), the Japan Science and Technology Agency (grant JPMJPR21D6), the Ministry of the Environment, Japan (grant 4-2001) and the Alexander von Humboldt Foundation. It was conducted in collaboration with researchers from Tohoku University, Osaka Metropolitan University, Fukushima University, and the National Institute of Genetics.

The large-scale study analysed more than 1,000 stool samples from people with diarrhoeal illness to harness two cutting edge tools.

Diarrhoea, a common symptom of infectious intestinal disease, affects an estimated 18 million people each year in the UK. However, despite its prevalence, traditional lab tests often fail to recognise its cause, especially when infections are caused by unidentifiable or emerging pathogens. This newly published study used metagenomic (DNA-based) and metatranscriptomic (gene or RNA-based) sequencing. Unlike traditional methods, these techniques do not rely on growing organisms in a lab. Instead, they detect and analyse the genetic material directly from patient samples.

Co-lead author, Dr Edward Cunningham-Oakes, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool said: “This is the UK’s largest study to compare traditional diagnostics with these next-generation tools. We not only found infections missed by standard tests, but we could see what the bugs were doing inside the gut — something standard diagnostics just can’t show.”

The work captures, for the first time, a comprehensive snapshot of the Salmonella gene expression directly from a human stool sample. The transcriptomic data provides new insights into how the bacteria survive and adapt after leaving the human gut. As Salmonella remains a priority diarrhoeal pathogen in the UK, the knowledge will be invaluable for helping scientists to target this dangerous pathogen.

The study’s key findings highlight the power of RNA tests in detecting hidden infections — including elusive parasites and RNA viruses — while also identifying which genes are active during infection. Remarkably, RNA remained stable in stool samples even without preservatives, suggesting it is more robust than previously thought. Notably, the ratio of RNA to DNA helped differentiate true infections from harmless gut microbes. By combining both DNA and RNA data, researchers gained the clearest and most accurate picture of the infection process.

Co-lead Professor Alistair Darby, Co-Director of the University’s Centre for Genomic Research said: “This study shows how genetic tools can revolutionise how we identify and understand intestinal infections. By understanding not just what’s there, but what it’s doing, we can improve public health responses, particularly around foodborne outbreaks.”

The findings could significantly impact how diarrhoeal diseases are diagnosed, managed, and studied in the UK and beyond — especially in light of the growing need for rapid, accurate diagnostics that don’t rely on outdated culturing methods.

The research also highlights the strategic role of Liverpool’s Centre for Genomic Research (CGR) and the new Microbiome and Infectious Disease (MaID) initiative, which is part of the Liverpool City Region’s Life Sciences Innovation Zone.

Professor Alistair Darby continued: “This is about more than diagnosing infections — it’s about building a platform for innovation in healthcare. Our previous work has shown that healthcare professionals are open to this. By making our data open-access, we hope to help other researchers, NHS labs, and public health agencies build on our work.”

Dr. Edward Cunningham-Oakes added: “Our results show that RNA, once thought too fragile to use in stool testing, can actually give us powerful insights into how infections work. That opens up new possibilities for diagnosing and treating these illnesses more effectively.”

The research, led by scientists at the University of Liverpool, including Salmonella experts Dr Blanca Perez-Sepulveda and Professor Jay Hinton, was funded by the NIHR Health Protection Research Unit in Gastrointestinal Infections (HPRU-GI), a collaboration between the University of Liverpool, UK Health Security Agency, and other partners.

“Until now, our understanding of fibroblast diversity has been based primarily on studies in animal models. This new review is the first to compare and integrate extensive human studies that have used modern single-cell technologies. This approach makes it possible to combine findings from different human studies, creating a comprehensive picture of the various origins and functions of human fibroblasts,” says Professor Sandra Franz, lead author of the study from the University of Leipzig Medical Center.

This deeper understanding of cellular heterogeneity opens up new avenues for the development of targeted therapies. In the future, it may be possible to specifically address certain fibroblast subtypes — for example, to promote tissue repair or to inhibit pathological processes such as tumour growth. This is particularly significant for regenerative medicine and the treatment of chronic diseases.

The authors of the study — Dr Marta Torregrossa, Professor Jan C. Simon, and Professor Sandra Franz (all from the University of Leipzig Medical Center), together with Dr Yuval Rinkevich (Helmholtz Munich) — are conducting joint research as part of the ZellTWund project. Their aim is to further characterise regeneration-promoting fibroblast subtypes and their roles in health and disease — thereby paving the way for new therapeutic approaches. Translating these findings into clinical applications remains a key challenge for the coming years, the Leipzig researchers conclude.

Researchers at Washington State University’s Mount Vernon Northwestern Washington Research & Extension Center demonstrated in a new paper that some strains of wild spinach are resistant to Fusarium wilt, a fungal disease that is a persistent problem for growers of commercial spinach seed, and they identified regions of the plants’ genome associated with that resistance.

The findings are important for seed growers in western Washington and Oregon, where a significant portion of the world’s spinach seed is grown and where the pathogen has long been a problem due to the acidic soils.

“We were very, very pleased we found some excellent resistance when we did the screening and then we followed up with the DNA sequencing and looking at where that resistance might be lying,” said Lindsey du Toit, a plant pathologist who has worked on fighting disease in seed crops for 25 years at WSU’s Mount Vernon NWREC.

Though the new paper, published this month in Scientific Reports, identified several varieties of wild spinach associated with resistance to Fusarium wilt, more study is needed to understand the genetic nature of the resistance. However, seed companies don’t have to wait to apply the findings — they can begin breeding hybrids with the wild spinach varieties that showed resistance.

“You don’t necessarily have to understand the mechanism of resistance in order to use it,” du Toit said. “This is a tool that’s available immediately to breeding programs.”

Spinach consumption has been growing dramatically around the world. In the U.S., the per-capita consumption of the vitamin-rich vegetable has more than doubled in the past 20 years, with a particularly strong market for baby leaf spinach.

Most of the domestic crop is grown in hot, dry regions such as California, Texas and Florida. But growing spinach seed requires a rare combination of seasonal conditions — long, dry summers that aren’t too hot. As a result, around a fifth of the world’s spinach seed is grown in the Pacific Northwest.

But those crops have little resistance to Fusarium wilt, which afflicts spinach by entering through the roots and blocking their ability to take up water. Seed growers have tried to manage this problem by rotating spinach crops on long timeline — a decade or more between plantings — and taking other measures to treat the soil with calcium carbonate to reduce the acidity.

Even so, the prospect of an expensive “wipeout” of an entire crop has remained a continual threat.

In the current study, du Toit and a former post-doctoral researcher in her lab, Sanjaya Gyawali, screened 68 varieties of wild spinach from the region where the plant originated — Uzbekistan and Tajikistan — and compared them to 16 cultivated varieties. Researchers from the University of Arkansas also participated in the study.

They found strong resistance to the pathogen in several wild varieties. They then identified the chromosomal locations associated with the most powerful resistance. Those locations — known as quantitative trait loci — can be used by breeders to introduce more resistance to Fusarium wilt into commercial lines using marker-assisted selection, a technique that uses DNA markers to select for desirable traits.

The work was funded in part by the Specialty Crop Research Initiative of the U.S. Department of Agriculture’s National Institute of Food and Agriculture. The project was also supported by WSU CAHNRS Hatch Projects, and the Alfred Christianson Endowment in Vegetable Seed Science.

University of California, Berkeley, astronomers have now discovered the first instance of a massive black hole tearing apart a star thousands of light years from the galaxy’s core, which itself contains a massive black hole.

The off-center black hole, which has a mass about 1 million times that of the sun, was hiding in the outer regions of the galaxy’s central bulge, but revealed itself through bursts of light generated by the spaghettification of the star — a so-called tidal disruption event, or TDE. In a TDE, the immense gravity of a black hole tugs on a star — similar to the way the moon raises ocean tides on Earth, but a lot more violently.

“The classic location where you expect massive black holes to be in a galaxy is in the center, like our Sag A* at the center of the Milky Way,” said Yuhan Yao, a Miller Postdoctoral Fellow at UC Berkeley who is lead author of a paper about the discovery recently accepted for publication in The Astrophysical Journal Letters (ApJL). “That’s where people normally search for tidal disruption events. But this one, it’s not at the center. It’s actually about 2,600 light years away. That’s the first optically discovered off-nuclear TDE discovered.”

The galaxy’s central massive black hole, about 100 million times the mass of our sun, is also gorging itself, but on gas that has gotten too close to escape.

Studies of massive black holes at galactic centers tell astronomers about the evolution of galaxies like our own, which has one central black hole — called SagA* because of its location within the constellation Sagittarius — weighing in at a puny 4 million solar masses. Some of the largest galaxies have central black holes weighing several 100 billion solar masses, presumably the result of the merger of many smaller black holes.

Finding two massive black holes in the center of a galaxy is not surprising. Most large galaxies are thought to have massive black holes in their cores, and since galaxies often collide and merge as they move through space, large galaxies should occasionally harbor more than one supermassive black hole — at least until they collide and merge into an even bigger black hole. They typically hide in stealth mode until they reveal their presence by grabbing nearby stars or gas clouds, creating a short-lived burst of light. These are rare events, however. Astronomers calculate that a massive black hole would encounter a star once every 30,000 years, on average.

The new TDE, dubbed AT2024tvd, was detected by the Zwicky Transient Facility, an optical camera mounted on a telescope at Palomar Observatory near San Diego, and confirmed by observations with radio, X-ray and other optical telescopes, including NASA’s Hubble Space Telescope.

“Massive black holes are always at the centers of galaxies, but we know that galaxies merge — that is how galaxies grow. And when you have two galaxies that come together and become one, you have multiple black holes,” said co-author Ryan Chornock, a UC Berkeley associate adjunct professor of astronomy. “Now, what happens? We expect they eventually come together, but theorists have predicted that there should be a population of black holes that are roaming around inside galaxies.”

The discovery of one such roaming black hole shows that systematic searches for the signature of a TDE could turn up more rogue black holes. The find also validates plans for a space mission called LISA — the Laser Interferometer Space Antenna — that will look for gravitational waves from mergers of massive black holes like these.

“This is the first time that we actually see massive black holes being so close using TDEs,” said co-author Raffaella Margutti, a UC Berkeley associate professor of astronomy and of physics. “If these are a couple of supermassive black holes that are getting closer together — which is not necessarily true — but if they are, they might merge and emit gravitational waves that we’ll see in the future with LISA.”

LISA will complement ground-based gravitational wave detectors, such as LIGO and Virgo, which are sensitive to the merger of black holes or neutron stars weighing less than a few hundred times the mass of our sun, and telescopic studies of pulsar flashes, such as the Nanograv pulsar timing array experiment, which are sensitive to gravitational waves from the mergers of supermassive black holes weighing billions of solar masses. LISA’s sweet spot is black holes of several million solar masses. LISA is slated to be launched in the next decade.

Transient outbursts

Because black holes are invisible, scientists can only find them by detecting the light produced when they shred stars or gas clouds and create a bright, hot, rotating disk of material that gradually falls inward. TDEs are powerful probes of black hole accretion physics, Chornock said, revealing how close material can get to the black hole before being captured and the conditions necessary for black holes to launch powerful jets and winds.

The most productive search for TDEs has used data from the Zwicky Transient Facility, originally built to detect supernova explosions, but also sensitive to other flashes in the sky.

The ZTF has discovered nearly 100 TDEs since 2018, all within the cores of galaxies. X-ray satellites have also detected a few TDEs, including two in the outskirts of a galaxy that also has a central black hole. In those galaxies, however, the black holes are too far apart to ever merge. The newly discovered black hole is close enough to the core’s massive black hole to potentially fall toward it and merge, though not for billions of years.

Yao noted that two alternative scenarios could explain the presence of the wandering black hole in AT2024tvd. It could be from the core of a small galaxy that merged with the larger galaxy long ago and is either moving through the larger galaxy on its way out or has become bound to the galaxy in an orbit that may, eventually, bring it close enough to merge with the black hole at the core.

Erica Hammerstein, another UC Berkeley postdoctoral researcher, scrutinized the Hubble images as part of the study, but was unable to find evidence of a past galaxy merger.

AT2024tvd could also be a former member of a triplet of black holes that used to be at the galactic core. Because of the chaotic nature of three-body orbits, one would have been kicked out of the core to wander around the galaxy.

Searching galaxies for off-center black holes

Because the ZTF detects hundreds of flashes of light around the northern sky each year, TDE searches to date have focused on flashes discovered near the cores of galaxies, Yao said. She and Chornock created an algorithm to distinguish between the light produced by a supernova and a TDE, and employed it to search through the 10,000 or so detections by ZTF to date to find bursts of light in the galactic center that fit the characteristics of a TDE.

“Supernovae cool down after they peak, and their color becomes redder,” Yao said. “TDEs remain hot for months or years and have consistently blue colors throughout their evolution.”

TDEs also exhibit broad emission lines of hydrogen, helium, carbon, nitrogen and silicon.

Last August, the Berkeley team discovered a burp of light that looked like a TDE, but its location seemed off-center, though within the resolution limits of the ZTF. The researchers suspected the black hole was indeed off center, and immediately requested time on several telescopes to pinpoint its location. These included NASA’s Chandra X-ray Observatory, the Very Large Array and the Hubble Space Telescope. They all confirmed its off-nucleus location, with HST providing a distance of about 2,600 light years — about one-tenth the distance between our sun and Sag A*.

Though close to the central black hole, the off-nuclear black hole is not gravitationally bound to it. Because the black hole at the core spews out energy as it accretes infalling gas, it is categorized as an active galactic nucleus.

Yao and her team hope to find other roaming TDEs, which will give astronomers an idea of how often galaxies and their core black holes merge, and thus how long it takes to form some of the extreme, supermassive black holes.

“AT2024tvd is the first offset TDE captured by optical sky surveys, and it opens up the entire possibility of uncovering this elusive population of wandering black holes with future sky surveys,” Yao said. “Right now, theorists haven’t given much attention to offset TDEs. They primarily predict rates for TDEs occurring at the centers of galaxies. I think this discovery really motivates them to compute rates for offset TDEs, as well.”

The 34 co-authors who contributed to the paper come from institutions in the United States, United Kingdom, Sweden, Russia, Germany, Australia and the Netherlands. ZTF is a public-private partnership, with equal support from the ZTF Partnership and the U.S. National Science Foundation.

Peering back in time to when the universe was younger than the Earth is now, the images span the period from around twelve billion years ago until one billion years ago. The new catalogue of images, soon to be published in the journal Astronomy and Astrophysics (A&A), includes nearly 1,700 galaxy groups. The research group’s impressive image of a galaxy cluster over 6 billion light years away is currently showcased as the European Space Agency’s (ESA) picture of the month.

‘We’re able to actually observe some of the first galaxies formed in the universe,’ says Ghassem Gozaliasl of Aalto University, and head of the galaxy groups detection team who led the study. ‘We detected 1,678 galaxy groups or proto-clusters — the largest and deepest sample of galaxy groups ever detected — with the James Webb Space telescope. With this sample, we can study the evolution of galaxies in groups over the past 12 billion years of cosmic time.’

The James Webb Space Telescope began operating in 2022. The largest telescope in space, its higher resolution and greater sensitivity have enabled astronomers to see farther and better than ever before. Because light travels at a finite speed, the further away an object is, the further back in time our image of it. By observing very faint, very distant galaxies — the faintest galaxies in this dataset are one billion times dimmer than the human eye can see — the team got a glimpse of what galaxies looked like in the early universe.

Galaxy groups and clusters are rich environments filled with dark matter, hot gas, and massive central galaxies that often host supermassive black holes, explains Gozaliasl. ‘The complex interactions between these components play a crucial role in shaping the life cycles of galaxies and driving the evolution of the groups and clusters themselves. By uncovering a more complete history of these cosmic structures, we can better understand how these processes have influenced the formation and growth of both massive galaxies and the largest structures in the universe.’

Cosmic family history

Galaxies aren’t scattered evenly throughout the universe. Instead, they cluster in dense regions connected by filaments and walls, forming a vast structure known as the cosmic web. Truly isolated galaxies are rare — most reside in galaxy groups, which typically contain anywhere from three to a few dozen galaxies, or in larger galaxy clusters, which can include hundreds or even thousands of galaxies bound together by gravity. Our own Milky Way is part of a small galaxy group known as the Local Group, which includes the Andromeda Galaxy and dozens of smaller galaxies.

‘Like humans, galaxies come together and make families,’ explains Gozaliasl. ‘Groups and clusters are really important, because within them galaxies can interact and merge together, resulting in the transformation of galaxy structure and morphology. Studying these environments also helps us understand the role of dark matter, feedback from supermassive black holes, and the thermal history of the hot gas that fills the space between galaxies.’

Because the new catalog includes observations that span from one billion to twelve billion years ago, scientists can compare some of the earliest structures in the universe with relatively modern ones to learn more about galaxy groups and how they evolve. Studying the history of galaxy groups can also help astronomers understand how the giant, brightest group galaxies (BGGs) at their centres form through repeated mergers — an area explored in depth across several of Gozaliasl’s recent publications.

‘When we look very deep into the universe, the galaxies have more irregular shapes and are forming many stars. Closer to our time, star formation is what we refer to as ‘quenched’ — the galaxies have more symmetric structures, like elliptical or spiral galaxies. It’s really exciting to see the shapes changing over cosmic time. We can start to address so many questions about what happened in the universe and how galaxies evolved,’ says Gozaliasl.